Hey.

I know this isnt about Modding. But i thought this forum would be appropriate to awnser somet of the questions i have. Its bout leds, and i know that when you case mod, you usually have leds, and i need some help.

Im building a clock in tech-ed, and i plan on having 12 leds (5000 mcd http://www.superbrightleds.com/leds/g_specs.htm ) One at each hour. I'm Slightly knowledged in this field of electronics. But i still need some help.

Ok, i bought 13 of those 5000 mcd lights, incase one burned out. I figured if i got the http://www.superbrightleds.com/cgi-b...gi?product=PCB Pcb board it would help. I bought the 9, and the 4. Making 13. I also bought a few things at radio shack, i bought 9v clips, 9v holders, 2 9v batteries, and wire. Now, i was planning on first powering the 9 led holder. So heres my equation. 3.6(led voltage)+3.6+3.6 = 10.8. If i have a 9v battery, the light wont be at full brightness, but close enough. Unless i powered 2 9v togehter, equaling 18v, the ohm equation would be... 7.2 = .02 * R. And R = 360. That would work, but then i would need 2 9v. So that clears 9 of the 12 leds on my clock.

The other pcb board dosnt say if its parellel or series. So im quite confused how i would wire this together. The guy at radio shak said i could have only one battery, like taking my 9V and splitting it into two, but that would ware the battery down soo much.

What my question is, For the 4slot led, what resistor would i need, And should i split the 9v into two leads. Also it would be helpfull if you tell me suggestions (first time) And anything i have done wrong. My aim is Darkillusion2008 if you would like to contact me there.

I will post pictures when done. Thankyou all.

first dont ask the guy at radio shack because they are just there to put things on the shelves and operate the register.
second how are you switching the LEDs? because that will effect your values.
dont try to drive more LEDs than the supply can put out (add the forward voltages together) unless you like dim lights and always run a current limiting resistor even if the supply is less than the forward voltage.
then once you get to it the formula to find the resistor you need is
supply voltage - total forward voltage
LED amperage rateing
(supply minus forward divided by the amperage rateing of the LED)

Hey, i thought u might all want top see how it turned out. Take a look, and tell me what u think.

http://home.comcast.net/~darkillusion/DSC00476.JPG
http://home.comcast.net/~darkillusion/DSC00478.JPG
http://home.comcast.net/~darkillusion/DSC00479.JPG
http://home.comcast.net/~darkillusion/DSC00480.JPG

turned out nice, i thought you were going to put it so when the hour hand reaches an hour the led for that hour will turn on. or you know what would be even cooler, have bi colored leds and then have them all glow green and then when the hour hand is on an hour then the led changes from green to red on that hour only. and it did that all the wayt around. that would be a challenge. sure i would impress your tech teacher

i have taken hostages. if your mom wants it back its up to you if it comes back clean, or in pieces.
nice clock bright.

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